Liquid flow regulator and monitor for corporeal infusion system and method of using the same

ABSTRACT

The specification is directed to a device for regulating and visually indicating the rate of fluid flow from a corporeal infusion system such as an intravenous infusion system. One embodiment of the disclosed invention includes the detection of the rate of flow of air into the container of sterile liquid to be infused into the patient. The flow rate of the liquid to the patient is then visually indicated in response to the detected rate of flow of air into the container. In another embodiment of the invention, a housing is attachable to the air inlet of a conventional corporeal infusion system and includes a valve therein for regulation of the flow of air into the liquid container of the infusion system. Regulation of the amount of air into the container directly regulates the flow rate of liquid from the container to the patient. An indicator scale on the housing visually indicates the flow rate of the liquid from the container in response to the measurement of the flow rate of air into the container. Other embodiments of the invention include utilizing a timer to control the length of infusion and utilizing an alarm system in order to maintain the liquid infusion to the patient at a predetermined level.

United States Patent Deaton [54] LIQUID FLOW REGULATOR AND MONITOR FORCORPOREAL INFUSION SYSTEM AND METHOD OF USING THE SAME [72] Inventor:David W. Deeton, Dallas, Tex. [73] Assignee: Ahldee Corporation, Dallas,Tex. 221 Filed: May 4, 1970 [2]] Appl. No.: 34,121

[52] [1.8. Ci ..137/551, 73/209, 128/214, 222/59 [51] Int. Cl. ..Fl6k37/00 [58] Field of Search 1 37/55 1; 73/198, 209; 128/214, 128/214 R;222/59 [56] References Cited UNITED STATES PATENTS 536,606 4/1895Crawford et a1. ..73/ 198 2,099,842 11/1937 Connell ...73/209 X2,852,024 9/1958 Ryan ..128/214 3 ,128,625 4/1964 Heineman ..73/2093,252,623 5/1966 Corbin et a1. ..222/59 3,363,461 H1968 Minkoff...73/198 X 3,500,366 3/1970 Chesney et a1 128/214 51 I May 2, 1972FOREIGN PATENTS OR APPLICATIONS 966,701 9/1957 Germany ..l28/214.2438,611 11/1935 GreatBritain ..128/214 Primary Examiner-Henry T.Klinltsiek Attorney-Richards, Harris & Hubbard 57] ABSTRACT the rate offlow of air into the container of sterile liquid to be infused into thepatient. The flow rate of the liquid to the patient is then visuallyindicated in response to the detected rate of flow of air into thecontainer. in another embodiment of the invention, a housing isattachable to the air inlet of a conventional corporeal infusion systemand includes a valve therein for regulation of the flow of air into theliquid container of the infusion system. Regulation of the amount of airinto the container directly regulates the flow rate of liquid from thecontainer to the patient. An indicator scale on the housing visuallyindicates the flow rate of the liquid from the container in response tothe measurement of the flow rate of air into the container. Otherembodiments of the invention include utilizing a timer to control thelength of infusion and utilizing an alarm system in order to maintainthe liquid infusion to the patient at a predetermined level.

12 Claims, 5 Drawing Figures TO PATIENT Patented May 2, 1972 3,559,529

2 Sheets-Sheet 1 VALVE PATIENT TIMER FIG.

v INVENTOR DAVID w. DEATON ATTORNEY Patented May 2 1972 2 Sheets-Shaet 2PATIENT FIG. 3

INVENTOR DAVID W. DEATON 3 g WW4.

ATTORNEY PATIENT LIQUID FLOW REGULATOR AND MONITOR FOR CORPOREALINFUSION SYSTEM AND METHOD OF USING THE SAME FIELD OF THE INVENTION Thisinvention relates to corporeal infusion systems, and more particularlyto a method and apparatus for regulating and monitoring the flow rate offluid supplied to a patient from a corporeal infusion system.

THE PRIOR ART It is necessary to administer liquids to hospital patientsin a wide variety of instances. Systems for administering liquids topatients, hereinafter generally termed corporeal infusion systems, rangefrom the commonly used intravenous fluid infusion systems to renalinfusion devices, gastro-intestinal infusion devices and cardiacinfusion devices. In all of these applications, it is of courseextremely important to carefully meter the amount of liquid which isinfused into the patient.

Corporeal infusion systems of the type described generally comprise acontainer of sterile liquid, an outlet connected through a flexible tubeto the patient and an inlet through which air is vented into thecontainer in order to displace the liquid drained from the container.Typical of such systems is the commonly used intravenous infusion systemwhich includes an inverted glass bottle filled with sterile liquid suchas a sugar solution and/or electrolytes and antibiotics. As the sugarsolution is drained from an intravenous bottle through the flexible tubefor infusion into the patient through a needle in the patient's vein,air is vented through the inverted cap of the intravenous bottle fordisplacement of the fluid drained from the bottle.

The most common technique for metering the liquid output fromconventional intravenous bottles has heretofore comprised the manualoperation of a mechanical valve in the liquid output tube with theoperator mentally counting the number of drops falling into the dripchamber of the intravenous bottle during a predetermined time period.This procedure has heretofore been carried out by nurses, and is bothtime consuming and subject to error. Moreover, such previous regulatingtechniques have had to be constantly watched and readjusted due to thefact that the drip rate from an intravenous bottle often tends to varyover a period of time due to changes in the bottle height and changes inresistance to flow in the system or patient.

Devices have been proposed for elimination of the manual counting of thedrop rate of an intravenous bottle, but such devices have generally beencomplex in nature and have required the direct regulation and monitoringof the liquid flow through the liquid output tube leading to thepatient. Such devices have ranged from devices which physically sensethe passage of liquid drops through the drip chamber of the intravenousbottle to flowmeter devices which are physically inserted in the tubeleading from the liquid output of the intravenous bottle to the patient.Prior devices installed in the liquid output tube have been required tobe sterile, and have often required expensive filters which tend to clogwhen heavy liquids are passed therethrough. Thus, such flowmeters haveoften not been usable to meter blood to a patient. Additionally, suchpreviously developed flowmetering systems installed in the liquid outputof corporeal infusion systems have tended to be difficult to bothcalibrate and operate due to variances in liquid viscosity from one typeof infusion to another.

SUMMARY OF THE INVENTION In accordance with the present invention,problems inherent in the direct metering of liquid flow from a corporealinfusion system are circumvented by the regulation and monitoring of thevented air flow into such containers which is necessary in order todisplace the liquid drained therefrom. The present invention thusoperates upon a constant viscosity gas such as air which thus providesan extremely accurate and stable regulation and monitoring system. Thepresent system may be utilized a number of times with difierentcorporeal infusion systems, with the use of suitable air filterstherein, due to the fact that only air is entrained therethrough. Thepresent system may be utilized on a wide variety of corporeal infusionsystems operating with liquids of large differences in viscosity withoutsubstantial recalibration, due to the fact that air is monitored andregulated in each instance.

In accordance with the present invention, a container of sterile liquidincludes an infusion outlet for directing liquid from the container tothe patient. Structure according to the invention is provided to controlthe volume of gas which displaces the liquid within the containerthereby controlling the flow of liquid through the infusion outlet.

In accordance with another aspect of the invention, an improvement isprovided for a corporeal infusion system including a container ofsterile fluid and an infusion outlet in the container for directing thefluid to a patient. An air inlet is also provided in the container forintroducing air into the container to displace the fluid drainedtherefrom. The improvement of the present invention comprises a valvefor attachment to the air inlet which is operable to selectively varythe How of air into the container to thereby regulate the flow of thefluid through the infusion outlet.

In accordance with yet another aspect of the invention, a device isprovided to visually indicate the flow rate of liquid from a corporealinfusion system wherein air displaces liquid within a container.Structure is provided to detect the rate of flow of air into thecontainer and structure is operable in dependence upon the detectionstructure for visually indicating the flow rate of the liquid from thecontainer.

In accordance with a more specific aspect of the invention, apparatus isprovided to selectively regulate the flow rate of liquid from a patientcirculatory infusion container which has an air inlet for admitting airto displace the liquid within the container. A valve is provided forconnection to the air inlet of the container and is selectively operableto vary the flow of air into the container. An indication device isoperable in response to the flow of air through the air inlet forvisually displaying an indication of the flow rate of the liquid fromthe container.

In accordance with yet a more specific aspect of the invention, a devicewhich accurately regulates the flow rate of liquid from an intravenousinfusion container includes a housing for attachment to the air inlet ofthe infusion container. A valve is disposed in the housing forregulating the flow of air into the container in order to regulate theflow rate of liquid from the container. An indicator is disposed in thehousing and is responsive to the flow of air through the housing forvisually indicating the flow rate of liquid from the container.

In accordance with yet another aspect of the invention, a method ofregulating the liquid flow to a patient from a corporeal infusion systemwherein air displaces the liquid within a container includes regulatingthe rate of flow of air into the container in order to obtain aproportional regulation of the liquid flow rate from the container.

In accordance with another aspect of the invention, a method is providedto indicate the flow rate of liquid to a patient from a corporealinfusion system wherein air displaces the liquid within a container. Theflow rate of air into the container is sensed and the liquid flow ratefrom the container is displayed in dependence upon the sensed flow rateof air.

DESCRIPTION OF THE DRAWINGS For a more complete understanding of thepresent invention and for further objects and advantages thereof,reference is now made to the following description taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 illustrates a somewhat diagrammatic view of one embodiment of theinvention for regulation of air into an intravenous infusion container;

FIG. 2 illustrates a somewhat diagrammatic view of a conventionalintravenous infusion system in combination with the present flowregulating and metering device;

FIG. 3 illustrates another embodiment of the invention and includes asomewhat diagrammatic illustration of a conventional intravenousinfusion system in combination with the present flowmeter device;

FIG. 4 is a block diagram illustrating the use of a timing circuit forcontrolling the supply of air to a conventional intravenous infusionsystem through the present flowmeter and regulation invention; and

FIG. 5 is a block diagram illustrating the use of an alarm system withthe regulation and flowmeter device of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, aconventional intravenous bottle or container is supported in theconventional manner by an upstanding support pedestal 12. The bottle 10is filled with a sterile liquid solution 14 which is to be infused intoa patient. For instance, the solution 14 may comprise a sugar solution,with electrolytes or antibiotics added in some cases. It will beunderstood that although an intravenous bottle 10 is illustrated, thepresent invention may be used on any one of a number of corporealinfusion systems wherein a liquid is to be infused into the body of apatient. Thus, the solution 14 may be infused into the veins or into thearteries of the patient. The bottle 10 and solution 14 may alternativelybe used as a renal infusion system wherein the patient is to beirrigated with water and/or antibiotics. Alternatively, blood may bemetered from the bottle 10 into a patient. I

A cap 16 is connected to the bottle 10 and includes an outlet aperturetherethrough to allow the liquid solution 14 to flow from bottle 10. Theliquid solution 14 falls into a drip chamber 18 and flows down aflexible tube 20 for infusion into the patient, not shown. Generally,the end of tube 20 is connected to a needle inserted into the patient.The bottle 10, cap 16, drip chamber 18 and flexible tube 20 are allconventional and are widely used throughout hospitals. Bottle 10 isgenerally comprised of glass, while the cap 16, drip chamber 18 andflexible tube 20 are generally comprised of plastic. A valve 22 may beused to coursely regulate the flow of fluid through the tube 20. Valve22 includes a screw member 24 which may be manually operated to compressthe tube 20 for regulation of the liquid flow therethrough. It should beunderstood that the illustrated intravenous infusion system is only onetype of several commonly used intravenous devices. However, all suchintravenous devices work according to the same operating principles andthe present invention may be used to regulate and monitor liquid flowfrom all such devices.

Cap 16 also includes a second aperture therethrough for venting of airor other gas into the bottle 10. The venting of air is to enable thedisplacement of the liquid solution 14 within the bottle 10 with air forproper operation of the infusion system. In a conventional intravenousinfusion system, an unimpeded air inlet, along with an air filter, isprovided in cap 16 to enable the venting of air into the bottle.

According to the present invention, a needle valve assembly 26 isconnected to the air venting inlet of the cap 16. Valve assembly 26comprises a needle member 28 which may be selectively rotated within avalve housing to vary the orifice through which air is admitted into thebottle 10. Valve assembly 26 thus allows selective adjustment of theflow rate of air admitted into bottle 10. An air filter 30 is attachedto the air inlet side of valve assembly 26 to enable only filtered airto be admitted into the bottle 10. Preferably, the valve assembly 26 andfilter 30 are integrally connected in a plastic housing. The'plastichousing includes a flexible tube 32 on the upper part thereof to enableattachment to the existing air inlet of a conventional intravenousbottle.

In operation of the present device, the valve assembly 26 is affixed tothe air venting inlet of a conventional intravenous infusion system, orto the air venting inlet of any other suitable corporeal infusionsystems used in hospitals or the like. The needle member 28 is thenmanually rotated to give the desired flow of air through the filter 30and the needle valve assembly 26, and through the venting aperture inthe cap 16 to the bottle 10. Due to the fact that the only air allowedto enter into the bottle 10 is controlled by the needle valve assembly26, the amount of liquid which passes into the drip chamber 18 may beprecisely controlled by the setting of the needle member 28. The airallowed to enter through the cap 16 bubbles through the liquid solution14 in the conventional manner, thereby allowing a predetermined amountof liquid to pass through the cap 16 into the drip chamber 18 andthrough the tube 20 to the patient. The valve 22 may be used for grossinitial liquid flow regulation if desired, but in many applications willnot be required.

FIG. 2 is an enlarged view of another embodiment of the inventionwherein a visual indication of the liquid flow rate from a corporealinfusion system is provided. Like numbers are used throughout thevarious figures of the application for like and corresponding parts. Theconventional intravenous bottle 10 is again illustrated, along with aconventional cap 16, drip chamber 18, and flexible tubing 20 whichsupplies the sterile liquid within the bottle 10 to the patient. Aconventional air filter assembly 40 is also illustrated which includes aone-way ball check valve 42. The ball member of the valve 42 operates toprevent leakage of the liquid solution by abutting against shoulders 44.An air filter 46 is connected to filter out impurities such as bacteriaand the like from the air. Filter assembly 40 is of conventionalconstruction presently found on commercially available intravenousbottle assemblies.

The present flow regulator and monitor is illustrated generally by thenumeral 50 and includes a flexible tubing 52 which seals against thefilter assembly 40 to enable the present device to be attached to aconventional intravenous bottle assembly. Tubing 52 communicates withthe outlet of a needle valve 54. The inlet to the needle valve 54isconnected to a tapered channel member 56 which houses a metal ball 58.A scale 60 is connected along one side of the channel member 56 andcontains calibrated indicia 62 printed thereon. The indicia iscalibrated in liquid drops per minute or in milliliters per hour. Thelower end 64 of the channel member 56 is open to the atmosphere. Theneedle valve 54 includes a needle member 66 which may be manuallyscrewed within the valve housing in order to vary the effective orificefor passage of air through the needle valve 54. I

The continuously tapered channel member 56 and the ball 58 operate as apressure compensated flow meter to provide a visual indication of theair flow through the monitor 50. When no air is flowing into the bottomof the tapered channel member 56, the ball 58 rests at the bottom of thechannel. When gas first enters the channel member 56, enough pressuremust be developed to overcome the weight of the ball 58 and raise it offthe open bottom of the channel member 56. A pressure difference is thendeveloped between the bottom and top of the ball 58 to cause the ball 58to rise in the channel and be suspended upon a cushion of air. The spacebetween the ball 58 and the interior walls of the tapered channel member56 increases in size due to the tapered configuration of channel 56 asthe gas flow increases and the ball 58 rises higher in the channel. Theball 58 ceases to rise when the pressure on the underside thereof issufficient to balance the effects of gravity on the ball.

In operation of the embodiment shown in FIG. 2, the assembly 50 isattached to the conventional air filter member 40 of an intravenous orother corporeal infusion system. The flexible tube 52 provides anairtight seal between the filter member 40 and the present assembly 50.Operation of the infusion system is initiated and liquid drops passthrough the liquid outlet in the cap 16 and drip into the drip chamber18. The liquid then flows down tube 20 to the patient.

In order to provide a metered flow of the sterile liquid,

within the bottle 10, the needle valve member 66 is rotated while theposition of the ball 58 with respect to the indicia 62 is observed. Whenthe ball 58 rises to the desired liquid flow rate indicia on the scale60, the proper liquid flow is being applied to the patient andadjustment of the needle valve member 66 is temiinated. Air flowsthrough the aperture 64 and upwardly along the channel member 56,through the needle valve 54, through the filter 46, through the one-wayball check valve 42 and into the bottle in order to vent the system. Dueto the fact that the supply of air into the bottle 10 is metered, theoutput of liquid into the drip chamber 18 is also proportionallymetered. The indicia 62 is calibrated in terms of liquid flow rate. Thepresent device thus monitors and regulates the input of air into theclosed bottle 10 in order to accurately monitor and regulate the outputof liquid from the bottle 10.

The use of the system shown in FIG. 2 eliminates many of the problemsheretofore experienced wherein regulating and monitoring operations wereattempted in the fluid outlet lines of corporeal infusion systems. Thepresent system is required only to meter air, and thus no problems areexperienced with the present invention when metering fluids withdifferent viscosities. It is well known that even sterile solutionscontained in intravenous bottles often change viscosities due to storagetime, difference in temperatures and the like. Such differences inviscosities have presented problems in flow meters which are required todirectly meter the liquid output from such intravenous bottles.

Prior metering systems have also often experienced difiiculties due toclogging and the like, and especially those metering systems utilizingliquid filters with relatively heavy viscosity liquids. Due to the factthat only air travels through the present flowmeter system, the presentsystem may be detached from one corporeal infusion system and utilizedon another infusion system, without the requirement of cleaning orsterilization. Such subsequent use of flowmeters is not generallypossible with prior systems which must be inserted into the sterileliquid output side of corporeal infusion systems. Another advantage ofthe present invention is that once set, the present device tends tomaintain the corporeal infusion system in a stable mode of operation.Prior systems wherein flowmeters were disposed in a liquid output of thecorporeal infusion systems tend to fluctuate in liquid output due todifferences in viscosity of the fluid being metered.

FIG. 3 illustrates yet another embodiment of the present invention, withlike numerals being utilized for like and corresponding parts previouslydescribed. This embodiment is somewhat similar to that shown in FIG. 2,with the exception that the needle valve assembly is removed from thepresent device and the conventional valve 22 is utilized in the liquidoutput side of the bottle 10 for flow rate control. The valve 22comprises a valve commonly used on conventional in travenous bottlesystems. A housing including a tapered channel member 56 is connected tothe filter assembly 40 which is found on conventional intravenousbottles. As previously noted, the filter assembly 40 includes a ballcheck valve 42 which seals against shoulders 44 in order to prevent theflow of liquid therethrough. A filter 46 filters the air passing intothe bottle 10. A ball 58 is movable along the tapered channel member 56and is maintained at a particular position in dependence upon the amountof air passing through the channel member 56. A scale 60 includesindicia 62 thereon for enabling a visual indication in drops per minuteor in milliliters per hour of the liquid being discharged from thebottle 10. The end of the tapered channel member 56 is open to theatmosphere.

In the operation of the embodiment shown in FIG. 3, the flowmeterassembly of the invention is attached to the air inlet of a conventionalintravenous infusion system. A screw member 24 of the conventional valve22 in flexible tube is regulated, while the position of the ball 58 isobserved. When the ball 58 rises to the position adjacent the desiredflow rate indicia on scale 60, adjustment of the member 24 is terminatedand the desired flow rate is applied to the patient through the tube 20.

FIG. 4 somewhat schematically illustrates another embodiment of thepresent invention. An intravenous infusion bottle 10 is supported abovea patient by a pedestal l2 and includes a cap 16 through which liquidfrom the bottle 10 falls into the drip chamber 18. The liquid is thenconducted through the flexible tube 20 and through the valve 22 forinfusion into the patient.

The device 50, as previously disclosed, is connected to the air inletaperture through the cap 16. Device 50 comprises a tapered channelmember 56, ball 58, a scale 60 and indicia 62 thereon in order toprovide a visual indication of the rate of flow of the liquid from thebottle 10 to the patient. However, instead of the lower end of thedevice 50 being open to the atmosphere, the device 50 is connected viaan air line to a solenoid controlled air valve 70 which is operated by atiming circuit 71. Air, or another suitable gas, is supplied through thevalve 70 when the valve is open, the air then passing through theflowmeter assembly 50 to the bottle 10. The timing circuit 71 maycomprise either a mechanical device or electrical circuit and may beselectively set for a desired time interval. After the expiration of thetime interval, the timing circuit 71 deactivates the solenoid controlledair valve 70 and flow of air into the bottle 10 is temiinated. Liquidinfusion to the patient is thus stopped.

FIG. 5 illustrates yet another embodiment of the invention, wherein analarm may be actuated when the flow of liquid to the patient exceedspredetermined high and low limits. A conventional intravenous infusionbottle 10 is supported by a pedestal l2 and supplies liquid through thecap 16, drip chamber 18 and flexible tube 20 to the patient aspreviously described. The present device 50 of the invention, previouslydescribed, is connected to the air inlet aperture through the cap 16.Control of the needle valve member 66 (FIG. 2) precisely controls theamount of air metered into the bottle 10 to precisely meter the amountof liquid supplied to the patient through the tube 20, as previouslydescribed.

A pair of sensing probes 72 are adapted to be positioned along thetapered channel member 56. The probes 72 are connected through a sensingcircuit 74 and through lead 76 to an alarm device 78. Alarm 78 maycomprise an audible alarm, energizable lights or the like.

In the preferred embodiment of the system shown in FIG. 5, the ball 58movable along the tapered channel member 56 is comprised of metal. Thesensing probes 72 are magnetic sensing probes which detect the presenceof a metal object. Alternatively, the probes72 may comprise lightemitting and receiving members which detect the passage of the ball 58thereby; The sensing circuit 74 generates an electrical signal only whenthe ball 58 moves from between the probes 72, in order to actuate thealarm 78.

In operation, the probes 72 are attached in accordance with the desiredflow range setting on scale 60. As long as the ball 58 remains betweenthe two probes 72, the alarm 78 is inactive. When the ball moves frombetween the probes 72, circuit 74 operates the alarm 78 so that anattendant may readjust the valve in the system to prevent harm to thepatient. Suitable sensing and alarm systems for operation in accordancewith the position of the metal ball in a flow meter are presentlycommercially available.

While the present invention has been described with the utilization ofneedle valve assemblies for adjustment of the amount of air allowed topass into a corporeal infusion bottle, it will be understood that othertypes of air valves may be utilized with the invention. For instance, asuitable air valve may include a housing with a flexible tube thereinfor transmission of air therethrough. A screw mounted in the housing maybe rotated in order to selectively compress the flexible tube in orderto adjust the orifice through which the air may pass. Other types ofmechanical metering valves commercially available may also be used withthe invention.

Additionally, although the present flowmeter has been illustrated ascomprising a pressure compensated type with a tapered channel and a ballmember, it will be understood that other type of flowmeters formeasuring the flow of a gas such as air may be utilized with theinvention. For instance, a disc type float could be utilized instead ofthe ball member illustrated in the drawings. Other types of air gas flowmeters usable with the invention comprise fixed or variable orificetypes, or flowmeters operating according to the manometer principle.

Although the present invention will be particularly useful withintravenous infusion systems frequently utilized in hospitalenvironments, the present technique will also be advantageous for usewith other types of corporeal infusion systems such as renal,gastro-intestinal and cardiac infusion systems wherein liquid is to bemetered to a patient from a container, the liquid being replaced withinthe container by a gas such as air. I

Additionally, although the present flowmeter has been illustrated as asingle tapered channel, in some instances it may be desirable to add atortuous input and output channel in connection with the illustratedtapered channel in order to provide stabilization of the indicator ball.Such a tortuous path might include a first vertical path generallyparallel to the present tapered channel and attached to the outlet ofthe largest end of the tapered channel 56 by a generally horizontallyextending channel. A second generally vertical channel would then bespaced apart from the tapered channel 56 and communicate with thesmallest end of the tapered channel 58.

Other configurations of flow meter will become apparent to one skilledin the art.

Whereas the present invention has been described with respect tospecific embodiments thereof, it will be understood that various changesand modifications will be suggested to one skilled in the art, and it isintended to encompass such changes and modifications as fall within thescope of the appended claims.

What is claimed is:

1. A device for visually indicating the flow rate of liquid from acorporeal infusion system wherein air displaces the liquid within acontainer comprising:

means for detecting the rate of flow of air into the container, and

means operable in dependency upon said means for detecting for visuallyindicating the flow rate of said liquid.

2. The device of claim 1 and further comprising:

a housing adapted to be connected to the air inlet of the container,

indicia on said housing calibrated in terms of liquid flow rate from thecontainer, and

a member movable along said indicia in dependence upon the flow of airinto the container, whereby the location of said member with respect tosaid indicia provides an indication of the flow rate of liquid from thecontainer.

3. The device of claim 2 wherein said member comprisesa ball elementmovable along a tapered channel through which air flows into thecontainer.

4. The device of claim 2 and further comprising:

means responsive to the position of said member for actuating an alarmwhen .the liquid flow rate varies beyond a predetermined value.

5. The device of claim 2 and further comprising:

timer means for controlling the time interval that air is supplied tothe container.

6. A device for accurately regulating the flow rate of liquid from anintravenous infusion container comprising:

a housing for attachment to the infusion container,

a valve disposed in said housing for regulating the flow of air into thecontainer in order to regulate the flow rate of liquid from thecontainer, and

indicator means attached to said housing responsive to the flow of airtherethrough for visually indicating the flow rate of liquid from thecontainer.

7. The device of claim 6 wherein said valve means comprises a needlevalve.

8. The device of claim 6 wherein said indicator means comprises:

a pressure compensated flowmeter having a member movable along a scalecalibrated in liquid flow rate increments.

9. The device of claim wherein said flowmeter com rises: a taperedchannel having a member movable therea long in response to air flowthrough said channel.

10. The device of claim 6 and further comprising:

means for actuating an alarm when the flow rate varies beyondpredetermined limits.

11. The method of regulating the liquid flow to a patient from acorporeal infusion system wherein air displaces the liquid within acontainer comprising:

regulating the rate of flow of air into the container in order to obtaina proportional regulation of the liquid flow rate from the container,and

visually indicating the liquid flow rate from the container by detectingthe flow rate of air into the container.

12. The method of indicating the flow rate of liquid to a patient from acorporeal infusion system wherein air displaces of liquid the fluidwithin a container comprising:

sensing the flow rate of air into the container, and indicating theliquid flow rate from the container in dependence upon the sensed flowrate of air.

1. A device for visually indicating the flow rate of liquid from acorporeal infusion system wherein air displaces the liquid within acontainer comprising: means for detecting the rate of flow of air intothe container, and means operable in dependency upon said means fordetecting for visually indicating the flow rate of said liquid.
 2. Thedevice of claim 1 and further comprising: a housing adapted to beconnected to the air inlet of the container, indicia on said housingcalibrated in terms of liquid flow rate from the container, and a membermovable along said indicia in dependence upon the flow of air into thecontainer, whereby the location of said member with respect to saidindicia provides an indication of the flow rate of liquid from thecontainer.
 3. The device of claim 2 wherein said member comprises a ballelement movable along a tapered channel through which air flows into thecontainer.
 4. The device of claim 2 and further comprising: meansresponsive to the position of said member for actuating an alarm whenthe liquid flow rate varies beyond a predetermined value.
 5. The deviceof claim 2 and further comprising: timer means for controlling the timeinterval that air is supplied to the container.
 6. A device foraccurately regulating the flow rate of liquid from an intravenousinfusion container comprising: a housing for attachment to the infusioncontainer, a valve disposed in said housing for regulating the flow ofair into the container in order to regulate the flow rate of liquid fromthe container, and indicator means attached to said housing responsiveto the flow of air therethrough for visually indicating the flow rate ofliquid from the container.
 7. The device of claim 6 wherein said valvemeans comprises a needle valve.
 8. The device of claim 6 wherein saidindicator means comprises: a pressure compensated flowmeter having amember movable along a scale calibrated in liquid flow rate increments.9. The device of claim 8 wherein said flowmeter comprises: a taperedchannel having a member movable therealong in response to air flowthrough said channel.
 10. The device of claim 6 and further comprising:means for actuating an alarm when the flow rate of liquid varies beyondpredetermined limits.
 11. The method of regulating the liquid flow to apatient from a corporeal infusion system wherein air displaces theliquid within a container comprising: regulating the rate of flow of airinto the container in order to obtain a proportional regulation of theliquid flow rate from the container, and visually indicating the liquidflow rate from the container by detecting the flow rate of air into thecontainer.
 12. The method of indicating the flow rate of liquid to apatient from a corporeal infusion system wherein air displaces the fluidwithin a container comprising: sensing the flow rate of air into thecontainer, and indicating the liquid flow rate from the container independence upon the sensed flow rate of air.